A report on my experience modifying my distributor and setting timing. (...Pardon my sometimes long-winded posts.)
First, the motor. A '73 340 that once had 13:1 pistons and a giant cam… an old race motor that was given to me. I rebuilt it myself 20+ years ago, though I've put only 75K-80K miles on it since.
It came to me with a cross-over oiling system (-AN line crossing valley to feed front mains), heads were ported to the max and polished fully. Chambers reworked, etc. I put hardened seats in them, fresh valves, Comp springs. Used forged 8:5 pistons, block was decked, align-honed, forged crank, rods side-clearanced, ...a ton of work had been done before. Block had been ground smooth inside with what appeared to be white epoxy paint throughout.
I "ruined" a good race motor to use on the street. Compression ended up about 8.7:1. Intake is a port matched LD-340 with 750 Edelbrock. Modified some headers and port matched. I tried to do everything as right as I could. Using 273 adjust. rockers. I am running a mild 284 Lunati Bracket Master cam. Compression test shows 155-160#.
But tuning was not my forte… I did finally did get it to run 13.95 at 98.5 mph two years ago on my yearly trip to the strip.
So with tips from this forum and elsewhere, I decided to tear apart my Mopar Performance distributor (the early version from '92 or so) So I welded up the slots and limited the advance from 17* (34 crank) down to 9*/18. (set with a degree wheel) It still has the stock springs, a mix of very light, the other very heavy. Upon installation I am getting only 13-14* out of it so I wonder if the heavy spring is working at all…?
So to get close to 34-35* I set the initial at a bit over 20* which the motor seemed to like (by rpm and vacuum gauge) My vacuum advance brings in 15* so I total out at just under 50*.
After a life time of setting timing on a lot of motors from 4-12* it just seems wrong to set it at 20+!!!!! Is this really OK. It ran cool, started easily when hot, and not a hint of detonation running on 87 octane fuel.
Anybody else running timing similar to this with their small blocks??? Should I get more in the mechanical and back off the 20 initial? Or am I OK?
First, the motor. A '73 340 that once had 13:1 pistons and a giant cam… an old race motor that was given to me. I rebuilt it myself 20+ years ago, though I've put only 75K-80K miles on it since.
It came to me with a cross-over oiling system (-AN line crossing valley to feed front mains), heads were ported to the max and polished fully. Chambers reworked, etc. I put hardened seats in them, fresh valves, Comp springs. Used forged 8:5 pistons, block was decked, align-honed, forged crank, rods side-clearanced, ...a ton of work had been done before. Block had been ground smooth inside with what appeared to be white epoxy paint throughout.
I "ruined" a good race motor to use on the street. Compression ended up about 8.7:1. Intake is a port matched LD-340 with 750 Edelbrock. Modified some headers and port matched. I tried to do everything as right as I could. Using 273 adjust. rockers. I am running a mild 284 Lunati Bracket Master cam. Compression test shows 155-160#.
But tuning was not my forte… I did finally did get it to run 13.95 at 98.5 mph two years ago on my yearly trip to the strip.
So with tips from this forum and elsewhere, I decided to tear apart my Mopar Performance distributor (the early version from '92 or so) So I welded up the slots and limited the advance from 17* (34 crank) down to 9*/18. (set with a degree wheel) It still has the stock springs, a mix of very light, the other very heavy. Upon installation I am getting only 13-14* out of it so I wonder if the heavy spring is working at all…?
So to get close to 34-35* I set the initial at a bit over 20* which the motor seemed to like (by rpm and vacuum gauge) My vacuum advance brings in 15* so I total out at just under 50*.
After a life time of setting timing on a lot of motors from 4-12* it just seems wrong to set it at 20+!!!!! Is this really OK. It ran cool, started easily when hot, and not a hint of detonation running on 87 octane fuel.
Anybody else running timing similar to this with their small blocks??? Should I get more in the mechanical and back off the 20 initial? Or am I OK?
